Healthcare providers, such as doctors and nurses, frequently use handheld devices when providing healthcare. Many of these handheld devices include electrical devices that must be powered by electricity. One example of such a handheld device is an otoscope, which includes a light to illuminate a patient's ear canal during an examination. It is sometimes desirable to adjust the electrical device, such as to increase or decrease the brightness of the light.
Some handheld instruments include a power cable that can be plugged into a wall receptacle to deliver power to the handheld device. The power cable limits the use of the handheld instrument to locations near a wall receptacle. The power cable is also inconvenient because it can inhibit free movement of the handheld device.
Batteries are sometimes used in handheld devices to overcome the drawbacks of power cables. While batteries do allow the healthcare provider to freely move the device independent of a wall receptacle, batteries have their own limitations. Batteries must be periodically recharged or replaced. Batteries are also slow to recharge, and so the handheld device may be out of service for some time. In addition, batteries have a limited life, and can be harmful to the environment if not disposed of or recycled properly.